Abstract
Previous research has shown that attending to two simultaneous visual tasks results in varying degrees of interference depending on the nature of the two tasks. One model postulates that different feature-coding mechanisms are equipped with independent finite pools of attentional resources (Morrone, Denti, & Spinelli, 2004). The present study extends our previous research (Maeda & Nagy, 2008 VSS) and tests the hypothesis that the parvocellular and the koniocellular pathways in the lateral geniculate nucleus tap independent pools of attentional resources. Observers searched simultaneously for a target in each of two spatially separated arrays of stimuli that were presented briefly. Targets that resulted in 75% correct performance for each array in single-task conditions were then used in the dual-task conditions. Based on the independent resource pool hypothesis, we predicted that searching for two targets that are coded by the feature-coding mechanisms within one pathway (within-pathway condition) would lead to more dual-task interference than searching for two targets that are coded by feature-coding mechanisms in two different pathways (between-pathway condition). Results yielded varying degrees of dual-task interference depending on the task combinations (i.e. within- or between pathways, target-distractor relationship and target appearance). Between-pathways task pairs generally resulted in very little interference (88% of single-task performance). Some within-pathway task pairs also resulted in very little dual-task interference (92 % of single-task performance), while other within-pathway task pairs produced substantial interference (69 % of single-task performance). Overall, results generally did not support the independent resource pool hypothesis. Results will be discussed further in terms of a multiple-resource model (Navon & Gopher, 1979), a shared resource sampling model (Miller & Bonnel, 1992), and a switching competition model (Duncan, 1980) of divided attention.